亚波长光栅调制的偏振稳定垂直腔面发射激光器研究

基于微光学技术设计得到了偏振稳定垂直腔面发射激光器结构, 将亚波长光栅结构集成在上分布布拉格反射镜表面, 光栅周期小于材料中光波长, 透射波和反射波中仅包含零级衍射, 避免了高级次衍射造成 的损耗. 集成光栅后不同偏振方向光阈值增益不同, 从而实现偏振控制. 实验结 果显示, 集成亚波长光栅结构后, 整个激射过程中偏振方向被固定在平行于光栅槽方向上, 获得偏振稳定激光输出, 正交偏振抑制比大于12 dB, 且阈值电流仅增大7.14%.     

Chaos synchronization and communication of the polarization modes for two unidirectionally coupled vertical-cavity surface-emitting lasers

We theoretically investigate the synchronization performance of the polarization modes of two unidirectionally coupled vertical-cavity surface-emitting lasers (VCSELs), where the master VCSEL subjects to polarization-preserved optical feedback and the slave VCSEL subjects to polarization-preserved optical injection. We demonstrate that high synchronization can be achieved between corresponding polarization components of the master laser and the slave laser. We also analyze the influence of the internal mismatched parameters on the synchronization performance. Furthermore, this system is used to dual-channel communication and the different transmitted digital information is respectively recovered at each polarization branch of the slaver laser successfully with the encryption scheme of chaos masking (CM). The results open an opportunity for multichannel chaotic communication by utilizing different polarization components in single-mode or multi-transverse-mode VCSELs.     

894nm高温垂直腔面发射激光器及其芯片级铯原子钟系统的应用

报道了自行研制的894 nm高温垂直腔面发射激光器(VCSEL)以及基于此类器件的芯片级铯原子钟系统的应用实验结果.根据芯片级铯原子钟对VCSEL在特定高温环境下产生894.6 nm线偏振激光的要求,对器件的量子阱增益及腔模位置等材料结构参数进行了优化,确定增益-腔模失谐量为-15 nm,使器件的基本性能在高温环境下保持稳定.研制的VCSEL器件指标为:20—90?C温度范围内阈值电流保持在0.20—0.23 m A,0.5 m A工作电流下输出功率0.1 mW;85.6?C温度环境下激光波长894.6 nm,偏振选择比59.8:1;采用所研制的VCSEL与铯原子作用,获得了芯片级铯原子钟实施激光频率稳频的吸收谱线和实施微波频率稳频的相干布居囚禁谱线.     

表面液晶-垂直腔面发射激光器阵列的热特性

液晶与垂直腔面发射半导体激光器(VCSELs)阵列结合可实现波长可调谐、偏振精确控制等,同时液晶的引入也会改变垂直腔面发射半导体激光器阵列的热特性,本文设计了表面液晶-垂直腔面发射激光器阵列结构,并开展了阵列的热特性实验研究.对比分析了向列相液晶层对VCSEL阵列热特性的影响,实验结果表明,1×1,2×2,3×3三种表面液晶-VCSEL阵列的阈值电流温度变化率最高可降低23.6%,热阻降低26.75%;同时,激光器阵列各发光单元之间的温度均匀性显著提高,出光孔与周围温差小于0.5℃.综上所述,VCSEL阵列中液晶层的引入不仅大大加速激光器阵列单元热量扩散,而且降低了有源区结温,提高了VCSELs激光器阵列热特性,为实现高光束质量的单偏振波长可控VCSEL激光器阵列打下了良好的理论和实验基础.     

表面液晶-垂直腔面发射激光器温度特性的研究

本文利用向列相液晶层作为激光偏振调控单元,涂覆于垂直腔面发射激光器（VCSEL）表面,测量并分析了不同温度下VCSEL正交线偏振光的阈值电流、峰值光功率和I-P特性. 实验结果表明：温度为293 K时,涂覆液晶后激光偏振第一跳变点和第二跳变点之间的电流值ΔI增大了2.2 mA,比无液晶时增大1倍. 温度为313 K、注入电流为3 mA时,两种正交线偏振光的光功率差ΔP由133.6 μW增大到248.8 μW,进一步增加了线偏振光的各向异性. 表面液晶层的引入有效地扩大了VCSEL的正交线偏振态稳定范围和光功率差,为实现液晶VCSEL高温单偏振稳定的设计和器件制备提供了理论和实验基础. 关键词： 垂直腔面发射激光器 向列相液晶 偏振态     

Synchronization of polarization mode of two unidirectionally coupled vertical-cavity surface-emitting laser and its application in communication

We theoretically investigate the synchronization performance of polarization mode of two unidirectionally coupled vertical-cavity surface-emitting laser (VCSEL) and propose an encryption scheme, where the phase of the polarization states of the master laser are modulated. It is demonstrated that high synchronization can be achieved between corresponding polarization components of the master laser and the slave laser. Moreover, two distinct synchronization regimes exist, complete synchronization and injection locking. The transmitted digital information is successfully recovered at each polarization branch of the slaver laser. The results open an opportunity for multichannel chaotic communication by utilizing different polarization components in single-mode or multi-transverse-mode VCSELs.     

Two-mode injection locking in vertical-cavity surface-emitting lasers

We report on the dynamics that accompany polarization switching induced by orthogonal optical injection in a vertical-cavity surface-emitting laser (VCSEL). As the injection strength increases, the VCSEL bifurcates to injection-locked steady states and time-periodic and possibly chaotic dynamics. Of particular interest is a two-mode injection-locking solution, i.e., locking of the two VCSEL polarization modes. A detailed stability analysis unveils new bistability mechanisms in optical injection problems.     

Vertical cavity surface emitting laser transverse mode and polarization control by elliptical holes photonic crystal

The polarization of traditional photonic crystal (PC) vertical cavity surface emitting laser (VCSEL) is uncontrollable, resulting in the bit error increasing easily. Elliptical hole photonic crystal can control the transverse mode and polarization of VCSEL efficiently. We analyze the far field divergence angle, and birefringence of elliptical hole PC VCSEL. When the ratio of minor axis to major axis b/a=0.7, the PC VCSEL can obtain single mode and polarization. According to the simulation results, we fabricate the device successfully. The output power is 1.7 mW, the far field divergence angle is less than 10°, and the side mode suppression ratio is over 30 dB. The output power in the Y direction is 20 times that in the X direction.     

基于亚波长光栅的VCSEL偏振控制研究

为了确定亚波长光栅在微电机械系统(MEMS)波长可调谐VCSEL不同位置(上DBR上表面、上DBR下表面以及内腔)中实现TE和TM偏振控制的光栅参数范围以及光栅在哪个位置时实现偏振控制最稳定,通过MATLAB建立MEMS波长可调VCSEL的模型,然后计算光栅在3种位置时上反射镜(包括空气隙和光栅)随光栅参数变化的反射率,以此来确定它们实现TE/TM稳定偏振的光栅参数范围(即高反射范围内的参数)。将各自的高反射所对应反射率减去相同光栅参数范围内TM/TE低反射对应的反射率,通过反射率差值确定光栅在哪种位置时MEMS波长可调谐VCSEL实现偏振是最稳定的。最后得出的结论是光栅在上DBR下表面几乎无法控制TM偏振,而将光栅放置于内腔中,无论是在TE偏振控制上还是TM偏振上都是最稳定的。在实现TE偏振稳定的参数范围内,TE的阈值增益比TM最小少10 cm~(-1);而在实现TM偏振稳定时,在TE偏振稳定的参数范围内,TE的阈值增益比TM最小少5 cm~(-1)。     

Polarization switching characteristics in a 1550nm VCSEL subject to circularly polarized optical injection

Polarization switching(PS) characteristics in a 1550 nm vertical-cavity surface-emitting laser(VCSEL) subject to circularly polarized optical injection(CPOI) are experimentally investigated.The results show that,under different biased current,a solitary 1550 nm VCSEL can oscillate at y polarization mode(y mode),two polarization components(PCs) coexistence or x polarization mode(x mode).The PS characteristics induced by CPOI for the VCSEL operating at y mode and x mode are analyzed and the evolutions of dynamical states with the injected power are discussed.Additionally,the mappings of nonlinear dynamical states are given in the parameters space of the injected power and frequency detuning.     

基于椭圆偏振光注入垂直腔表面发射激光器的正交偏振模式单周期振荡产生两路光子微波

提出了基于椭圆偏振光注入下垂直腔表面发射激光器(VCSEL)输出的正交偏振模式单周期(P1)振荡来同时获取两路光子微波的实现方案, 并进行了相关仿真研究. 结果表明: 在合适的参数条件下, 一个自由运行的VCSEL(定义为主VCSEL, M-VCSEL)可输出椭圆偏振光, 其X偏振分量和Y 偏振分量具有相同的激射频率; 将M-VCSEL输出的椭圆偏振光注入到另外一个VCSEL(定义为副VCSEL, S-VCSEL), 在给定主副VCSEL间频率失谐的条件下, 通过选择合适的注入强度可使S-VCSEL 中两个偏振分量均呈现单周期(P1)振荡, 从而可获得两正交的光子微波信号; 随着注入强度的增加, 光子微波的频率以及功率均呈现增加的趋势; 结合微波频率、功率以及输出光谱中第一边带和第二边带的幅度差在由注入强度和频率失谐所构成参数空间下的分布图, 可确定获取高品质微波信号的优化注入参数范围.     

Wavelength switching based on quantum-dot vertical-cavity surface-emitting laser

This study investigates, for the first time, static and dynamic wavelength switching characteristics of the 1.3 ??m quantum-dot vertical-cavity surface-emitting laser (QD VCSEL). The free-running QD VCSEL with ??1 and ??2 state innately is injected by a laser source with ??1 state. When the injection power exceeds the threshold power, the dominant state of the QD VCSEL changes from ??2 to ??1 state. Results of this study demonstrate that the wavelength switching based on a 1.3 ??m QD VCSEL has a simpler and more cost-effective configuration than those of previous systems.     

Analytical modelling of end thermal coupling in a solid-state laser longitudinally bonded by a vertical-cavity top-emitting laser diode

The intrinsic features involving a circularly symmetric beam profile with low divergence, planar geometry as well as the increasingly enhanced power of vertical-cavity surface-emitting lasers (VCSELs) have made the VCSEL a promising pump source in direct end bonding to a solid-state laser medium to form the minimized, on-wafer integrated laser system. This scheme will generate a surface contact pump configuration and thus additional end thermal coupling to the laser medium through the joint interface of both materials, apart from pump beam heating. This paper analytically models temperature distributions in both VCSEL and the laser medium from the end thermal coupling regarding surface contact pump configuration using a top-emitting VCSEL as the pump source for the first time. The analytical solutions are derived by introducing relative temperature and mean temperature expressions. The results show that the end contact heating by the VCSEL could lead to considerable temperature variations associated with thermal phase shift and thermal lensing in the laser medium. However, if the central temperature of the interface is increased by less than 20~K, the end contact heating does not have a significant thermal influence on the laser medium. In this case, the thermal effect should be dominated by pump beam heating. This work provides useful analytical results for further analysis of hybrid thermal effects on those lasers pumped by a direct VCSEL bond.     

矩形结构垂直腔顶发射激光器的偏振特性

为了获得高功率的偏振激光,对矩形结构的980 nm大口径顶发射垂直腔面发射激光器(VCSEL)进行了研究.实验结果显示,对于400 μm×80μm出光口径的矩形VCSEL器件,在工作电流内,水平偏振光和竖直偏振光共同存在,并且水平偏振光一直占据主导地位;而且水平偏振光的光谱相对于竖直偏振光有蓝移.这些现象和理论模型的分...     

表面等离子体调制单模面发射激光器的研究

对单模面发射半导体激光器的研究随着其应用的不断扩展而引起了人们的广泛的重视,应用多种方法可以提高其输出功率并改善其模式抑制比.利用金属表面等离子体纳米结构调制的方法可以获得单模面发射激光器输出功率的提高,理论计算表明这种方法增强效应可达近50%. 关键词： 表面等离子体 单模面发射激光器 模式选择     

Ultrafast switching dynamics of nonlasing modes of vertical-cavity surface-emitting lasers

Single-mode vertical-cavity surface-emitting lasers (VCSELs) have been investigated with ultrafast optical modulation. After injection of a subpicosecond laser pulse into the VCSEL cavity, nonlasing modes were excited and produced optical beating in the emission of the VCSEL. After these oscillations have died down, when the VCSEL is operating at high power and when the injected laser pulses exceed a power threshold as well, the injected laser pulses can induce the lasing to switch to a normally nonlasing mode with crossed polarization. Our measurements of the decay time of the nonlasing modes at low injected pulse energy are consistent with the interpretation of this switching as enabled by increased lifetime of the nonlasing modes at high power.     

各向异性光反馈注入的垂直表面发射激光器的矢量偏振模转换机理

数值研究了各向异性光反馈注入的垂直表面发射激光器(VCSEL)的矢量偏振模转换机理,研究结果表明,首先,当注入电流接近阈值电流时,由VCSEL的外部参数和偏振器控制的光反馈注入量中各偏振模的能量决定VCSEL 输出的偏振态.其次,由偏振器控制的各向异性光反馈注入引起的VCSEL输出偏振态呈周期性变化.另外,当由偏振器控制的反馈注入量中的x^偏振和y^偏振模能量相当时, x^偏振模和y^偏振模之间竞争激烈,而激光器外部微小的扰动都会打破这两种偏振模竞争 关键词： 各向异性光反馈 垂直表面发射激光器 矢量偏振模     

Power-induced polarization switching and bistability characteristics in 1550-nm VCSELs subjected to orthogonal optical injection

The polarization switching(PS) and polarization bistability(PB) characteristics of a 1550-nm vertical-cavity surfaceemitting laser(VCSEL) subjected to orthogonal optical injection are systematically investigated.The simulated results show that the PS and polarization-resolved nonlinear dynamical states of the VCSEL are critically dependent on the changing paths of the injected power.The polarization dynamics for different scanning directions of the injected power is presented to explain the polarization evolution during the formation of PS.In the case of forward scanning injected power,with the increase of frequency detuning level between the VCSEL and the injected light,the injected power required for PS gradually increases for negative frequency detuning but exhibits fluctuations for positive frequency detuning.In the case of reversely scanning injected power,the injected power required for PS displays fluctuant changes within the whole frequency detuning range.Specifically,PS may disappear under certain negative frequency detuning and large bias current.Furthermore,the hysteresis width as a function of the frequency detuning is calculated,and the regions for the appearance and disappearance of PB have been determined in the parameter space of the bias current and frequency detuning.     

Investigation of the mode splitting induced by electro-optic birefringence in a vertical-cavity surface-emitting laser by polarized electroluminescence

The mode splitting induced by electro-optic birefringence in a P-I-N InGaAs/GaAs/A1GaAs vertical-cavity surface- emitting laser （VCSEL） has been studied by polarized electroluminescence （EL） at room temperature. The polarized EL spectra with E｜｜[110] and E ｜｜ [150] directions, are extracted for different injected currents. The mode splitting of the two orthogonal polarized modes for a VCSEL device is determined, and its value increases linearly with the increasing injected current due to electro-optic birefringence; This article demonstrates that the polarized EL is a powerful tool to study the mode splitting and polarization anisotropy of a VCSEL device.     

Thermal analysis of high-index-contrast grating (HCG)-based VCSEL

A 3-D thermal analysis of 870 nm high-index-contrast grating (HCG)-based vertical cavity surface emitting laser (VCSEL) by using finite volume method (FVM) is presented in this paper. The HCG-based VCSEL is modeled by applying a steady-state 3-D heat dissipation model. Temperature distribution profile and thermal resistance (R_th) of the device are investigated by inserting the heat source value into the thermal simulation. Also, this analysis is performed for a conventional VCSEL operating at the same wavelength and under the same injected current as well as the same geometric sizes. The analysis shows that the maximum temperature inside the HCG-based VCSEL is lower than that inside the conventional VCSEL.